4. Checking the Data (Verification & Validation)

Data must be checked to make sure they have been entered properly and are accurate. The two main ways of doing this are ‘verification’ and ‘validation

Remember operators also have to make sure that the data entered in, is accurate, because if you put Garbage In (rubbish) you will get Garbage Out or GIGO

 

1. Data Verification

A common verification procedure is for an operator at a keyboard to be asked to confirm the details of the data displayed on the screen by a simple‘Is this correct Y/N?’ message.

At the BA check-in desk the operator checks each passenger’s details using the documents they bring with them and by asking them questions where necessary.

In other systems, the data is entered twice (either by the same operator or by two different operators working together).

Any difference between the two sets of entered data is highlighted to the user, who is asked to enter it again. Verification is commonly used to confirm a new password.

 

2. Data Validation

Validation checks are made by the software in the computer system.

Validation checks make sure that the correct type of data is entered properly at the correct point in the input process. British Airport Authority’s airport billing centre at Hillington carries out validation on all the data about landings and departures that are entered into the system.

Examples of Validation Check

a. Presence Check

This checks to make sure that a data item has not been completely left out. For example, if a field is missed out on a form, the software automatically generates an 'alert' that the field is empty when you want to continue to a next step.

b. Range Check

This ensures the data entered lies within given limits. In the airport example, the hour of the flight departure is between 0 and 23 inclusive, and the minute of the flight departure is between 0 and 59 inclusive. Numbers entered which lie outside this range automatically generates an alert.

c. Field Length Check

This checks that the correct amount of numbers or characters has been entered. The BA system will check that the correct number of digits has been entered for the ticket number, and the flight number.

 

d. Field or Data Type Check

This makes sure the correct type of data is entered. It makes sure, for example, that numbers are not entered into the passenger name field which expects text. The shot below checks that the date entered makes sense. If it doesn't an error message is generated.

 

 

e. Check Digit.

This is a number calculated by the computer to make sure that the other numbers in a sequence have been entered properly. It is used to make sure that the PIN that people use with their credit cards to pay for their seats on the aircraft has been entered correctly.

As another example check digit is nearly always used with bar codes. The last number in a bar code is a check digit. When a bar code is scanned, a formula is applied to the bar code and the result compared to the final number. Any differences between the computer generated number and the last number on the bar code generates an alert.

 

 

 

What you have to do!

Either in a new Word Document or in your Brain. Under a Sub Heading Checking Data - Validation and Verification complete the following tasks.

1. Explain what type of check would be made on data entered into the AOS to prevent a flight departure time of 25:10 being entered?
2. The airport billing system validates data being input to the system. What is validation?
3. Describe the data verification being carried out at the BA check-in desk.
4. What method is used to make sure bar codes have been entered correctly?
   

 

 

What you should now be able to do!

• Describe the difference between Data Verification and Data Validation.

• Provide different examples of Data Validation techniques.

• Explain the purpose of the check digit in a bar code and;.

• Explain how it is used to validate the bar code when it is scanned..

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Continue to 5. CDP Cycle: Data Processing